Undertow
by nb41
Summary: Spock and Kirk struggle to survive the fallout from being in the wrong place at the wrong time during a diplomatic mission. A post-STID adventure during the five year mission.
1. Chapter 1

Jim grimaced and tried not to fidget in the oppressive heat of a bright, windless, Erisian afternoon. The humidity was so thick, even Spock was sweating, and Jim reminded himself once again to commend Uhura for suggesting they skip the dress uniforms.

The two delegations were spread out opposite one another on a large, plain platform situated at the bottom of a large, bowl-shaped, outdoor arena. Thousands of colorfully clothed, indigenous spectators looked on, packed into the seats and standing in some of the aisles.

Jim forced his attention back on the central Erisian, whom Uhura had introduced as the people's President, because she was about to respond to the lengthy introduction Jim and Uhura had just given. She was a short, willowy individual named Njoras, and her bronze and green skin was a sharp contrast to her pale gray crown of braided hair filaments and the bright, cyan outfit she wore. The rest of her party were similar in attire, though not appearance; Erisians were a diverse species, with a broad range of body shapes and forms. They were by and large bipedal and had at least two arms—all of those here on the platform fit that description-though their heads could have anything from long, silky hair to short, spiked clumps to a rough, bark-like covering, and they moved with an undulating grace that could play tricks on the eye. Their thick, waxy skin varied from blue to green to coppery red to rich brown.

"We are pleased to accept the delegation from the United Federation of Planets, and hope that your time spent here will strengthen our relationship. Your journeys have led you far and wide, as have ours in this region of the Galaxy, and surely there must be mutual benefits to be had in the sharing of our findings."

A blessedly short response, for which Jim was grateful. They all began shuffling around on the platform to the places they would stand while Njoras gave a speech to those who'd gathered to catch site of the visitors. _Almost there_, he told himself, then winced as a muscle in his neck spasmed, sharp and painful. He rubbed at it, making use of the distraction of everyone moving around so he could do so unnoticed.

Three members of the Erisian delegation wore black outfits, and one of these directed the _Enterprise_'s delegation on where to stand and in what arrangement. Uhura made a gesture to them and murmured a phrase that sounded different from the primary language, and they seemed to regard her for a long moment before moving on to other duties. Uhura cut a sideways glance at Jim, and he acknowledged it with a nod.

The Erisians had not been forth-coming about their assistants, referring to them only as 'Ponosoi'. In general they resembled Erisians, but never wore the same color of clothing, and Uhura had indicated they didn't speak the primary Erisian languages amongst themselves. She hadn't, unfortunately, been able to arrange a private conversation with one, despite numerous attempts, and the files from the first contact mission decades earlier didn't really have much to say about them. It was a mystery Jim wanted to unravel without causing an incident, if they could.

Once they were re-arranged on the platform, Njoras began her speech to the gathered crowd. Jim concentrated on the various textures of the fabric in her outfit as a way to stay focused. He wasn't sure why his mind was wandering so much, but thinking was becoming difficult. Her voice rose and fell in a steady cadence; Uhura had indicated it was something to do with how they established context when speaking.

His eyes started to water. He blinked hard against the sensation and felt a tear slide down one cheek. Embarrassed, he reached up to wipe it away, and stared in surprise when his hand came away covered with something thick and blackish red.

One of the Erisian diplomats had noticed and was staring at him. She said something in their language and pointed, and everyone except Njoras turned to look at him.

Even Spock's eyes widened a fraction. "Captain," he said, reaching for him.

A high-pitched whining sound built in Jim's ears, and everything seemed to slow to a crawl. The air felt too heavy to breathe, and somewhere, someone was shouting.

Pain spiked in his head, sharp and deep and blinding, and he collapsed to his knees. He felt Spock's hand under his shoulder, trying to help him stand. His awareness was shrinking down and inward to that sound, which was getting closer and louder all the time. His vision swam, and his eyes snapped to someone in the crowds standing tall amongst the teaming morass of spectators. Their mustard and black robes flared in a sudden breeze, and their long, fine, dark blue hair gleamed in the sun.

The individual gestured, and the whining sound turned to a shriek.

The platform exploded into chaos.

* * *

He clawed his way back to consciousness, fighting an amorphous and unnameable force that sought to hold him under. This was no mere nightmare, and a conviction-that if he lost this battle much worse would come-fueled his struggle. Something deep inside him gave way, and the grip loosened, allowing him to writhe free.

He opened his eyes and saw only darkness. The air smelled moist and held the tang of minerals and earth and decay, and he was laying on his side. The ground under him was smooth like worked stone, and hard and cold, and amplified the fact that he was bruised and battered just about everywhere possible. He heard breathing, his own and someone else's. He could feel them close by.

He started to say something and a hand clamped over his mouth firmly. Every single survival instinct he had fired at once, yet his captor was more than strong enough to hold him immobile. Panic reared its ugly, ancient head, only to be doused when a familiar voice whispered close to his ear, "Captain."

_Spock_. He relaxed and went still, hoping that conveyed recognition and understanding. It seemed to, because Spock released him. He spoke in a voice so low Jim had to strain to hear him. "The stadium was attacked."

Jim shuddered, a hundred questions or more demanding answers, and Spock continued his explanation. "The rest of the crew successfully beamed back to the ship, but the _Enterprise_ was unable to lock on to our signals through the fighting. When the attack seemed to stop, the Erisians raised a shield around the stadium and refused to lower it to allow us to leave. I was negotiating our return to the ship when they were attacked again, from these tunnels, and the stadium subflooring collapsed."

"Any injuries among the crew?"

"I do not know."

Jim didn't think he imagined the concern in Spock's voice. He started to ask about the attackers when his his back and abdominal muscles cramped and seized, and he grit his teeth against any sounds he might make. Spock held him still until the spasm had passed. Overhead they heard movement and voices; they came closer, then moved further away.

Jim's heart hammered in his chest, and he remembered the black fluid coming from his eyes just before the attach. He tried to slow his breathing, and turned his head so he could speak into Spock's ear. "What's wrong with me."

"I am uncertain, though I believe this is involved. I found it in your tunic." Spock pressed something no bigger than the first joint of Jim's thumb into one of his palms, and he felt along the hollow body and needlepoint head of a dart. He remembered his overall discomfort on the platform, and wondered when he'd been shot.

"Poison?"

"Possibly."

"But why would they want to kill me?"

"I do not believe you were the intended target."

If Jim had just botched someone's political assassination, there was much more happening on the planet than the Federation or Starfleet new about, which would explain why Spock was hiding them. "We have to get back to the ship. We can't get the Federation caught up in whatever this is."

"Agreed. My communicator and tricorder are functional, but yours are not. We have no signal here, but if we can find our way clear of these tunnels, we may be able to contact the _Enterprise_ and escape unnoticed."

More movement overhead. Jim nodded his agreement, and they waited in tense silence until the sounds faded. Spock guided him to his feet, and they began to feel their way along the tunnel walls, taking slow, careful steps and staying as quiet as possible.

Now that he was moving, Jim realized that he hurt everywhere. It wasn't just the soreness of bruises and blunt trauma, but something deeper, an ache behind his eyes and in his chest. He felt strange in his own skin, like it didn't fit anymore, and his head was-

Jim jerked his foot back as he almost stepped into a hole of uncertain depth. Spock helped lead him around it. "How long since you've heard anyone?"

"Forty-five minutes."

Had they really been moving for that long? He realized he couldn't be sure, and tried not to worry about what it might mean. "Think we can risk a light?"

"I believe it would be prudent to do so."

They only had the emergency lights which socketed into the tricorders, but those were as good as floodlights in the black nothing around them. Spock turned his on at the lowest setting, bringing the level up after their eyes had adjusted.

The tunnel floor was worn down in a fashion which suggested the work of machinery; judging by the numerous cracks, splits, and holes, it was also very old. In contrast, the walls were uneven and varied from bumpy to jagged to smooth, poking out and curving in at random intervals, and the arced ceiling rose anywhere from ten to fifteen meters high.

"Lava tube?" Jim asked in a low voice. Spock stepped closer to the wall and ran a hand along the bronze-black stone.

"Most likely. Their stadium may have been built over a caldera."

Jim crouched down to touch the floor. "But they evened out the ground."

"It would make them more suitable for travel, or moving goods."

Jim stood, wincing as his joints popped and ached. Spock frowned at him, and Jim shook his head. "It can wait."

Though Spock didn't contradict him, Jim could see apprehension in his eyes, and chose to ignore it. They continued onward, guided by the soft glow of the light and Spock's knowledge of geology.


	2. Chapter 2

The further they walked, the more concerned Spock became. Lava tubes could be miles long, and though the captain made no complaints he was getting worse as time progressed. Spock began to worry over the wisdom of avoiding the Erisians in hopes of making good their own escape; even if they'd intended to use Jim and Spock as bargaining chips for Federation help with a domestic conflict, at least they might be able and willing to help Jim at the same time. Convincing Jim to go along with such a plan would have been difficult, though Spock was reasonably sure he could manage it if he had to.

They stopped frequently, not because Jim requested it but because Spock wanted him to, and it was a sign of his deteriorating condition that he didn't complain or argue.

During one such rest the sound of movement propelled them into a shallow depression in the tunnel wall. It had just enough space for the two of them to squeeze into, and at this proximity Spock could feel the captain was abnormally warm. They doused the light and held perfectly still, waiting.

Spock couldn't see the approaching group from his position, but their lights were a dull glow on the opposing wall as they came down an adjacent, intersecting tunnel. None of them spoke; the only sound was the shuffle of their movement. When they reached the intersection, their lights bobbed down a different fork than the one Jim and Spock had followed, leading them away once more.

They waited in the alcove, unmoving and barely breathing, until Spock couldn't hear the group anymore. He risked a step forward, paused, then reached behind himself and tugged at the hem of Jim's tunic. Jim followed close behind him, and they resumed their path, leaving the light off and feeling their way with their hands on the wall.

They made it another fifty meters before rounding a bend and coming face to face with a group of Erisians who had hooded their lamps and placed them into small depressions to keep the light from spreading.

The Erisians brought their weapons up in an instant, save for one individual in bright yellow and black robes, who just stared at them.

Jim and Spock stopped dead in their tracks, and Jim cut a look to him, his mouth set in a grim line. They held out their empty hands in front of them at the same time. The robed individual gestured at them, and Jim lowered his hands. Spock followed suit.

"You are far from the rest of your delegation," that one said.

Spock saw recognition in Jim's features, and he even mustered a weak smile. "There was a little problem with the floor. That stadium sure could use some renovations."

Some of the Erisians made a hissing sound; Nyota had said it was their indication of humor or amusement, but Jim watched them warily regardless. The robed one's eyes roved over Jim in turn, like they were noting his condition as compared to Spock.

"You're Ponosoi," Jim said, and some of the small party tensed, though the individual in the bright robes was not one of them.

"Yes," they said. Spock studied them; they had an air of command and authority about them, and the others cast furtive glances their way, watching how they interacted with Jim the same way Spock watched Jim interact with them.

"What did the Erisians tell you of us?" they asked.

"That you're a separate race." Jim coughed hard and wiped at his eyes. His fingertips came away dabbed with black.

The leader tipped his head, regarding Jim with greater scrutiny. "Is that all they said?"

Jim's breathing was labored, but Spock thought he could see him thinking the last three days over with excruciating care. "We couldn't help but notice there wasn't a single Ponosoi in a leadership position. Or any position of power."

Nyota had pointed it out to them on the first day. Spock felt understanding settle on him in a cold rush.

The leader tsked, and Spock suspected the sound was something like a Human's laugh. "We are biological constructs," they said, almost spitting the last word. "The Erisians made us to be their slaves."

* * *

Further explanation came in small snatches of conversation as the Ponosoi lead them through the winding lava tubes to the caverns where they lived. The leader identified himself as Qigora, and his lieutenant was the slim, lime-skinned Biraphi, but the rest did not offer their names.

The Ponosoi had been created by the Erisians to serve as an expendable labor pool, and were barely treated as 'people' despite how they outlived Erisians by decades and were a good deal more resilient to the planet's many diseases. Over the centuries handfuls of them had escaped into the wilds of the continent, hiding themselves deep in the caves that sprawled beneath the jungle-covered surface, where they'd built their own society. Every now and then an Erisian would defect and join them, and after a time one of those had turned out to be a scientist that was able to engineer them with the ability to procreate.

That had been the real turning point. Now able to reproduce on their own, their numbers had risen to the point where they could mount a proper revolt, but they lacked the industrial power the Erisians had. Even with Erisians abandoning their own people to join the Ponosoi's cause, it wasn't enough to make up for the head start the Erisian government had in terms of sheer resources.

"So you sought to infect one of their own leaders with this contaminant, and turn them into one of you," Spock said. "Then they would have no choice but to consider you from your own perspective."

Biraphi's face twisted. "Just so. Unfortunately," she examined Jim with narrowed eyes, "our aim was poor. We must apologize; it was not our intention to do this. We only wanted to expose the Erisians' duplicity."

Jim ran a hand through his hair and nodded. Spock imagined in other circumstances he might not accept an apology so easily (and especially not if it had been anyone but himself), but they had no choice. "Is it contagious?"

She shook her head. "No. It is very fragile-it is a wonder it has had any effect on you at all."

Jim coughed a morbid laugh. "I tend to be lucky like that," he said. Spock was sure Dr. McCoy would have agreed whole-heartedly.

If Biraphi thought Jim's comment was amusing, Spock couldn't tell. "The scientists should be able to fix you. They are adept at such things." She paused to look over her shoulder towards Qigora, then spoke in a lower voice. "But I must warn you. They will seek to bargain with you over it."

Spock raised an eyebrow. "Bargain for what?"

"Your assistance."

Spock saw Jim go rigid. One of his hands formed a fist, then slowly relaxed. "Thanks for the head's up."

She flicked her fingers-maybe that was a form of Ponosoi acknowledgement-and pulled away, no doubt wishing to avoid drawing Qigora's attention. Spock traded a concerned glance with Jim, who sighed and rubbed at one temple.

"This is now, officially, going down in my report as a shitty mission."

* * *

One of the benefits of the Ponosoi leading them was that they had supplies. Jim didn't seem interested in eating, but water he was willing to take, and any time they stopped to drink Spock scrutinized him.

The physical changes were minor at first: patches of olive green and gray mottling on his skin; the strange, red-black tears; a faint copper color staining his fingernails. As their journey continued, though, they intensified.

The changes to his eyes were the most worrisome to Spock. The outer edge of his irises now had a glossy black ring that shown silver in certain lights, and sometimes Spock thought he saw dark green creeping from that new border into the sclera. The later effect came and went; when Jim was more lucid, the whites were clearer (if bloodshot), but when his gaze wandered Spock saw distinct veins of gleaming emerald.

As punishing as Qigora's pace was, Spock worried it wasn't fast enough.

During their last rest break, Jim settled himself down on a low, stone shelf. While Spock scanned him with a tricorder, Jim said, "I don't know what this is doing to me, but it's pretty bad."

"Indeed, Captain, your breathing is erratic and-"

"That's not what I mean." Spock looked up from his tricorder, and saw a tremor pass through Jim. "It's doing something to _me_. To my-head."

"Your head?"

"My mind. I keep hearing things, things that aren't there. Like, music, or voices when no one's talking. I know I'm not-I'm trying not to listen to it but it's getting hard not to. It's getting hard to concentrate." Jim groaned and doubled over, face stricken, and Spock forced himself to keep still lest they draw too much attention to themselves. He didn't want to risk that there was a point Jim might reach past which the Ponosoi would refuse to help.

"Goddammit," Jim hissed under his breath. After several more seconds he straightened and took a deep breath. Spock thought the color edging out from the beds of his fingernails was darker now, and had a metallic sheen.

"We need to get this fixed soon."

"We will, Captain."

Jim looked unconvinced. "Listen. If they can't-"

"It would be unwise for us to entertain possible courses of action until we have a better grasp on what may or may not be done." Spock was pleased his voice remained steady as he said it, because the sudden flare of emotion that backed his interruption was anything but rational or logical, and at its core was a simple truth: he had not run Khan down through the desolation of San Francisco just to lose Jim to something so capricious and random as standing in the wrong place at the wrong time.

Jim stared at him, then laughed; the soft, dry sound was more like a wheeze. "You and Bones. Like...two peas in a pod, with how you handle me."

"I am not sure Dr. McCoy would appreciate the comparison, nor the analogy you have used to express it."

Another laugh, this one more like himself. Spock tried to let it reassure him.

Jim rubbed at his eyes. "We're moving again."

So they were. Qigora gestured with his head further down the tunnel, and Spock nodded. He helped Jim back to his feet, and they resumed what Spock hoped was their journey to a cure.


	3. Chapter 3

When they rounded the last turn, the damp, heavy air gave way to a fresh, warm breeze, and the tunnel's shape and direction became uniform. Here the walls had been carved with complex calligraphy that, to Spock's eyes, appeared similar to the Erisian written language, and a reddish orange algae that reflected the Ponosoi's lights lined the etchings and brought to mind the magma which had formed their pathway. The lava tube terminated into a T-intersection, with a wide, bay window overlooking a bright space set between the two new routes. Qigora murmured something to Biraphi, who came to join Spock and Jim.

"Qigora will assemble the council and call for the scientists." She gestured at the window. "Come, let me show you."

The rest of the party split and left down the two halls. Spock watched Qigora's retreating form until it was lost around a distant turn, then moved to join Jim and Biraphi.

Ill as he was, Jim sucked in a breath at the sight, and even Spock could not deny it was impressive. The window opened halfway up the wall of a well-lit cavern that was unevenly rounded and close to a kilometer across. Bulbous lamps that appeared to be formed from clumps of bioluminescent plants and algae dangled from various surfaces and flooded the immense space with pale yellow, white, and blue light. Enormous stalactite formations descended from the roof; windows carved into them revealed their interiors had been hollowed out like crustacean shells, with central, spiral staircases leading between discrete alcoves and rooms. Walkways enclosed in a clear material (perhaps they were semi-solid forcefields like the _Enterprise_ used) connected the stalactites, their backbones gleaming with the distinct sheen of a metal-ceramic composite. More structures had been carved from the smooth bumps that protruded from the cavern's walls, and in some of these Spock saw complex machinery, sprawling gardens, and even manufacturing.

Far below, half the cavern floor was covered in water. Small boats skimmed across the surface, which alternated between glassy smooth and wind-rough, and Spock saw that many of the tunnels exiting into the cavern were very small and covered with grates. No doubt these provided fresh air, while others served as exhaust outlets. He spied algae farms at one end of the enormous lake, and a fishery at another.

"Beautiful, no?" Biraphi asked, and Jim nodded.

"Incredible."

"This is not the only such colony. But it is the largest, and the oldest."

Spock considered Biraphi, and noticed that Jim was doing the same. She was taking an awful risk in giving them such information, which said a great deal about her desire for their trust. It also indicated she understood how precarious the situation was, considering Jim's deteriorating condition.

As if to underscore that, Jim groaned and put a hand to the wall for support. "So. About those s-scientists."

"Yes. This way."

* * *

Biraphi took them straight to the colony's research ward. Ponosoi stopped to stare at them as they passed, whispering and pointing at Jim. In the brighter light his condition looked much more severe, and Spock schooled himself to patience. He re-positioned himself so that Jim was walking between him and Biraphi, making Jim harder for the by-standers to see.

The medical labs were cobbled together from salvaged equipment that ranged in quality, yet for all that they were clean and their staff efficient. Biraphi left them with the doctors, who led them to an examination room that had a forcefield entrance. Spock wondered at that, until it occurred to him the room might very well have once been a containment cell. Waste not, want not, as Dr. McCoy might have said.

The doctors settled Jim upon the table and took blood and tissue samples; they were careful with him, and Spock told himself that had nothing to do with the way he was watching every single thing they did. When they were done, they gave Jim a considerable supply of water to drink, then went to run their tests.

Jim laid on the table, looking dazed. If Spock prompted him he would talk, but was otherwise silent. Eventually Biraphi returned, telling Spock the scientists would see him now.

"Can you give us a minute?" Jim asked. She made that short gesture with her hands, the same she'd used earlier, and stepped into the hall, well out of earshot.

Jim took a long, slow breath. "You remember what she said, about them wanting to bargain."

"Yes, Captain. I imagine support will be the first thing they request."

"Right." He shivered. "Tell them no."

"Captain-"

"No."

"We could-"

"_No_." Jim looked away towards the wall, his eyes unfocused. "We're not dragging the Federation into a global dispute, and definitely not over me. That's final."

"We may be able to convince them it is enough that we will present the situation to the Federation."

Jim swallowed and faced him again. "You know that's not what they want. It's not what the Erisians wanted either, they just didn't get a chance to ask."

"Be that as it may, I believe bringing the case of this planet to the Federation is a reasonable course of action, and one we would have undertaken regardless of either side's present actions. The Ponosoi will be able to supply ample evidence to support the severity of their situation."

Jim closed his eyes and took a handful of uneven breaths. "Don't offer to sway the Admiralty or anyone in the Diplomatic Corps. If the Federation decides to weigh in on this, it has to be based on the merits of the Ponosoi's case, not anything to do with us. That's an order."

Diplomacy might not have been the captain's forté, but politics was another matter. If Commander Spock of the _Enterprise_, who had defeated and then captured the Augment Khan and been instrumental in saving Earth from the same fate as Vulcan, came down on one side or the other, it would have substantial impact.

Reluctantly, Spock said, "Understood, Captain."

His voice soft, Jim went on, "And don't agree to do it if anyone _asks_ you to. That's also an order."

The conversation was a chess match which Spock was losing. "I will not."

They stayed like that for some time, Spock waiting and Jim looking at the end of his strength. "Okay. Now promise me you won't offer or agree to anything ridiculous that I haven't thought of."

"Captain?"

When Jim opened his eyes, the sclera was marbled with green. One of Spock's hands formed a fist. "Like, I don't know, yourself as a hostage, or-" He trembled. "Or something like that."

"I do not know what use they could make of-"

"Just promise, dammit."

Jim put enough emotion into his quiet, hoarse voice that Spock was surprised into silence. Then, "I promise I will not make any such offers, nor entertain them if they are made."

"Okay." Jim's eyes fluttered shut and his breathing slowed. Spock checked his pulse and, finding it steady, left to join the committee. A handful of doctors flowed into the room from the hallway after him.

* * *

The skies roiled with dark green and black clouds, and in the distance, the sirens wailed. Tornado sign for sure.

He sprinted towards the shelter, but the river lay between him and safety, already heavy with floodwater and rising even as he watched. The rickety footbridge he'd charged over with such abandon as a child swayed like a town drunk, threatening to break apart at any moment.

Wind tore at him and turned the tall, fat grass into thousands of tiny whips that stung his arms and legs. Between gusts he thought he heard voices, but when he scanned the fields there was only him, fleeing across the endless expanse of grass and stone.

He glanced back and saw the funnel cloud start to descend from the raging supercell; it was strange and terrible, formed of fire and lightning and smoke in addition to the inky clouds. Beyond it, further overhead, a brilliant, soft-edged, blue-white disk of light stretched across the otherwise dark sky.

When the twister touched down he thought he heard the whole of the world groan, and that spurred him to new speeds and put his eyes on the bridge once more. He kept running, and it seemed to follow, or maybe that was just its size and his fear.

At last, the bridge was under his feet. Just as he reached midspan it crumbled.

The water closed over his head and the shock was like an electric pulse all through him. He fought for the surface, frantic, gasping when he felt the frigid wind on his face and in his lungs. He used pieces of the bridges' remains to claw his way to the opposite bank, but it was slow going, and the tornado had continued to move in his direction.

He heard the voices again, and realized they were in the water and the wind, saying the same thing over and over: _Let go_.

Instinct told him that would be disastrous, so he tried to climb up the riverbank, only to find it was too steep for his exhausted, cramped muscles. He dug his nails into the loose soil and grass and held on with everything he had even as the black, icy water dragged at him.

The tornado tore apart everything in its path, growing as it consumed. Even in its roar he heard the words.

_Let go_.

When the tornado reached the river they converged into one stream of darkness and fury. He knew he shouldn't look, and did anyways, staring over his shoulder. They stretched up into the raging skies, leading to the burning halo of light like the remains of an unfortunate world that had strayed too close to a black hole.

Their combined strength was too much for him to resist, and much worse than that was the realization that he didn't want to fight anymore.

His fingers lost their grip on the riverbank, and the flow swallowed him and drowned him in euphoria.

_A very different Jim Kirk opened his eyes_.


	4. Chapter 4

Given the sight which greeted Spock when he first sprinted into the hall, it was difficult to comprehend how the Ponosoi treating Jim had escaped with their lives. On the other side of the forcefield lay the remains of the examination room: equipment and furniture torn apart and scattered like an angry child's toys, walls dented and gouged, cabinets smashed open and their contents spilled all over the floor. Behind Spock, the physicians who hadn't been injured were treating those who had. Broken bones were the most common injury, though a few had also been beaten soundly. After reassuring himself that none of them were going to die of their injuries, Spock looked back at the examination room.

Jim (_no, that is_ not _Jim_, something in him insisted) hadn't figured out how to get the forcefield barrier down, though a control panel's mangled wires indicated he'd made an attempt. He was pacing among the ruins like a caged predator, though after a moment he stopped, and his eyes locked onto Spock.

Only an inner ring of his irises remained blue; the rest was silver over black with an outer band of green that bled into the sclera. His fingernails gleamed copper against his fingers, which had a verdigris quality to them, and at various points the rest of his skin was mottled with patches of dusty olive and black spots.

The changes in his outward appearance weren't the real problem, though, because no matter how much an individual changed physically there were things which were undeniably and always them. If one took the time to observe they could always be identified.

Spock had catalogued these things about Jim Kirk over the last three years, and not a single one of them was present in the being standing in front of him now, no matter that he wore the captain's blood-stained, ragged uniform and spoke with his voice.

"Spock," he said, and smiled. It was full of leashed fury. "How about you let me out of here and we get back to the ship."

"I believe that would be ill-advised at this time."

He threw back his head and barked a laugh. "Why? I think I'm done changing, mostly." He examined his hands, stretching his fingers and then forming fists. "It feels good. We don't need to stay here anymore."

"On the contrary-we must administer the antidote and wait to be sure it will completely clear the contaminant from your system."

"Clear it?" He stepped closer to the forcefield. Instinct told Spock to back up, and he squelched the reaction. "Why would I want to do that? I've never felt this good before."

"As good as you may feel, the results are not without their dangers. We must reverse the process."

He raised his eyebrows. "What? Oh, you mean," he gestured at the room behind him, "all this. I just got a little out of control. It's nothing to worry about. Won't happen again."

"I do not believe Dr. McCoy will see it that way."

His teeth flashed. "Who the fuck cares what that mother hen thinks," he snarled, then sucked in a breath and shook himself out. "I'm fine. We need to get back to the ship. Leave these idiots to sort out their own problems." His eyes narrowed. "That's an order."

"I am afraid it is not an order I can nor will follow."

They regarded one another for a long time, then this thing which wasn't Jim moved to the disassembled control panel. "Then I guess I'll just have to go by myself," he said in a soft, feral voice, and tapped a button on the wall.

The other's plan became clear to him in that moment: Spock was the only one with a working communicator. This creature might not look like Jim Kirk, but he could sound like him, and the computers might very will still accept his command override codes. Once he was on board the _Enterprise_ it would be much too late to stop him.

But first, he needed to get Spock into the room and within striking distance.

The forcefield dropped, and the thing that had been and might still be Jim lunged at him.

He was fast like this, and strong, as well as ruthless; his first blows broke a rib and almost an arm to go with it. Muscle memory from hours spent in hand-to-hand combat training reasserted itself, saving Spock from graver injuries, and they began to grapple. Spock was at a significant disadvantage, because while he didn't want to kill, the thing that wasn't Jim had no such reservations.

"Captain. _Jim_. Please hear me."

"I can hear you just fine, Spock." He denied Spock the leverage necessary to apply a nerve pinch, evidence that at least some of the captain's memories were present.

_But that does not make it Jim_. "_You_ are not the captain."

"Of course I am." They shifted their holds on one another, each bidding for supremacy. "This is his body. This is his voice. These are his thoughts."

"And yet you are not him."

"It's easier for you to tell yourself that, isn't it? I can't be Jim Kirk, because if I am, then _this_ is Jim Kirk." Spock had missed the subtle change in his grip, and found himself shoved against the edge of a table, making the broken rib explode with pain. The creature spun him into a wall, which Spock managed to take with his shoulder rather than his head as was intended. He saw a group of Ponosoi burst into the hall, projectile weapons drawn.

"Do not fire! Let me subd-"

The creature had chosen to ignore the Ponosoi and instead charged at Spock. He slammed him against the wall again, hard enough to knock the wind out of him, then shifted his grip to Spock's throat, fingers poised to crush it and teeth bared. "You need to stop talk-"

Something in his eyes changed, and he released Spock and staggered back with a strangled cry. Spock sagged against a nearby cabinet, gasping as he tried to regain his breath, and watched the creature double over.

He raised his head, and it was undoubtedly Jim behind the oddly colored eyes. "Spock," he said. "Knock me out."

"Captain-"

Jim made a frustrated sound and fell to his knees. "Hurry, I can't hold it back much longer."

The Ponosoi watched Spock, their weapons at the ready. Biraphi hovered next to them, and Spock thought he owed their restraint to her involvement.

Spock pushed to his feet and closed the distance between himself and Jim. Jim was shaking and had wrapped his arms around himself like he might fly apart at any second.

Spock saw the change start to claw its way back out of him again. He pressed his fingers down at Jim's neck juncture. Jim went rigid, his green and black eyes rolled back, and he collapsed.

* * *

He awoke from a nightmare of tearing things and people and _Spock_ and planets and whole galaxies apart with his bare hands to the soft sounds of the _Enterprise_'s medbay and McCoy scowling at him over a tablet, injector in hand. He struggled to accept the new reality, because the old one was still fresh in his mind's eye, hammering at him with the voice of the person he'd always been terrified of becoming.

"Welcome back," McCoy said, and punctuated his greeting with the shot.

That small act of normalcy, so routine for the two of them, swept aside the last of his confusion. The injection didn't hurt, and along with the heavy, detached feeling encasing him he suspected he was on one hell of a painkiller.

"Good to _be_ back." His throat hurt to use, and his voice was a whisper. He narrowed his eyes. "I _am_ back, right?"

"Looks like," McCoy replied as he paged through a report on his tablet. "Your tests are clear, aside from you being beat to hell. Spock's not finding any trace of the contaminant anymore, and he said the data from those two Erisian scientists measures up."

"Spock. Is he okay?"

McCoy made a low sound. "He's fine. Busy terrorizing the Erisians over this mess and making a nuisance of himself over you, depending on which he thinks he can get away with at any given point in time."

"What about everyone else?"

"Well I was a little worried Sulu and Uhura were going to drag us into an armed conflict, they were pretty pissed." He met Jim's eyes over the tablet. "No injuries from the group that beamed up immediately after the attack, though."

Relief flooded him, along with a clear and nauseating memory: Spock's neck in his hands, and the certainty he could kill him with a minimal amount of effort. "You're sure Spock's alright?"

"Positive. He's got some bruises and a broken rib, but M'Benga says the later should clear up in a week or so."

_A broken rib_. So much less than he'd been trying to do, but so much more than he could forgive himself for.

He shut his eyes and nodded, and a sharp, "Hey," from McCoy had him opening them again. He tucked his tablet under one arm. "Do _not_ even think of blaming yourself for that."

"I could've killed him." I _wanted_ to kill him.

"You mean the thing you were turning into could have killed him."

"It was still me."

"Oh, like hell-"

"Captain."

McCoy halted his lecture at the sound of Spock's voice, glanced over his shoulder, and stepped aside. "Commander. So good of you to join us."

Jim winced as he took in Spock's condition. 'Some bruises' was the understatement of the year: dark green and purple ringed Spock's throat in a vibrant, unmistakable pattern, and the bulk of a thorough taping around his left side shown through his tunic. His movements were careful and hesitant, and he held himself like his back was troubling him.

"Shit. Spock, I'm sorry."

"As Dr. McCoy has already said, Captain, you do not have anything to be sorry for."

Jim couldn't believe what he was hearing. "Have you looked in a mirror?"

"Lieutenant Uhura told me I resemble you after one of your more eventful nights during the Academy."

McCoy snorted and shook his head. Jim stared at them, then focused on Spock. He couldn't partake of their amusement; anxiety made his throat tight. "I wanted to kill you. I almost _did_."

Concern sobered McCoy, but Spock spoke first. "You did not succeed in killing me, nor harm me in any permanent capacity. Furthermore, I believe any measurements as to the possibility of your success to be a fruitless exercise in blaming yourself for that which you could not hope to prevent." He waited, maybe to let Jim absorb all of that, then continued. "As for wanting to kill me, I can assure you that the contaminant had you wanting many things you would not otherwise ever consider, including endangering your crew. I think it reasonable to conclude, then, that you were not yourself, nor in control of your actions."

Jim licked his lips and stared down at the blanket drawn over him, trying to decide if it was as impossible to believe Spock as it felt. He looked up when McCoy spoke.

"Listen to him, will you? Of all the things to take credit for, going crazy after being shot with a biological weapon shouldn't be on the menu."

He sighed. "I guess."

"You guess."

"Captain, I would encourage you to-"

"Okay!" Trying to raise his voice was a mistake, and he rubbed at his throat. "Okay, I won't-I'll try to stop blaming myself."

McCoy narrowed his eyes. "Try?"

"I will. I _will_ stop blaming myself."

McCoy relaxed. "See? Was that so hard?"

"I'll let you know when I've actually managed to do it." Before McCoy could make a response to that, Jim asked Spock, "Did the Ponosoi go for a deal to bring their case to the Diplomatic Corps?" McCoy grunted and pulled out a CNS monitor.

"Yes. With help from the one named Birpahi."

Jim frowned around the device as McCoy pressed it to his temple. "I thought she was Qigora's lieutenant."

"It turns out she is also a member of their ruling Council. They are all expected to serve with the Defense Corps for a minimum of one Erisian year, in a non-leadership position."

Jim blew out a breath. A lucky break. "And the Erisians?"

"They are insisting none of what the Ponosoi say is true."

"Of course they are." The biological weapon was not going to go over well with Starfleet, but then the chances the Erisians didn't have their own stockpile (and hadn't used said stockpile at some point) were slim to none, seeing as one of their own scientists had made the Ponosoi's contaminant. Fortunately, those kinds of things were Starfleet's and the Diplomatic Corps' problem, and not Jim's or Spock's.

His eyes strayed back to the bruises on Spock's neck. Not Spock's, at any rate.

In the light, judgmental tone he had perfected, Spock said, "I believe you agreed to not blame yourself."

Jim refused to meet Spock's eyes. "I said it might take me some time to get there."

"Maybe I'll just keep you here until you do," McCoy said as he pocketed the monitoring device. Spock nodded agreement.

"At the very least, he will have to remain until he is fully recovered."

"Well conveniently, I'm the one who makes that call. Isn't it nice how these things work out?"

"I can't believe you two," Jim muttered. He burrowed back into the pillows and told himself he wasn't sulking.

"Not sure why you're the least bit surprised. The way I hear it, you think Spock and I are two peas in a pod."

Jim glared at Spock over McCoy's shoulder, trying to radiate _Goddamn you, Spock_, which was hard with the sedatives and painkillers and whatever else combining to make him feel like so much tissue paper. Worse, he could swear Spock looked smug.

"Well, you are," Jim said.

"In what way?" McCoy asked, his skepticism plain.

"_Every_ way."

"Somehow I doubt Spock appreciates being equated to an irrationally emotional Human."

Jim couldn't resist. "He'll have to stop acting like one, then."

Spock raised an eyebrow at Jim, then said to McCoy, "You are often overly emotional, Dr. McCoy, it is true. However, you also endeavor to ensure the captain does not cause undue harm to his own person, and seek to guide him in his duties, both of which are entirely rational and logical goals. I therefore cannot be wholly insulted by such a comparison."

"Why thank you, Commander, that might be the nicest thing you've ever said about me."

"It was not my intention to be nice, Doctor, merely accurate."

"Well maybe you overshot a little."

"That is a distinct possibility."

Jim shut his eyes and murmured, "I think I'm done blaming myself." The medication swept the waking world away, and if either of them responded, he didn't hear it.


End file.
